Rotary furnace

ABSTRACT

A rotary furnace having its discharge end leading to a conical extension that communicates with a plurality of circumferentially spaced cooling tubes and wherein the conical extension carries an annular member on which a bearing ring is fixed.

United States Patent 1191 1 51 Nov. 5, 1974 1 ROTARY FURNACE [75] Inventor: Manfred Durr,Oelde,-Germany [73] Assignee: Polysius AG, Neubeckum, Germany [22] Filed: Aug. 14, 1973 [21] Appl. No.: 388,197

[30] Foreign Application, Priority Data [56] References Cited UNITED STATES PATENTS 7/1928 Lindhard 432/106 3,358,977 12/1967 Jensen 432/80 3,502,139 3/1970 Anderson 432/81) 3,751,217 8/1973 Schosslcr et a1. 432/81) FOREIGN PATENTS OR APPLICATIONS 64,404 3/1946 Denmark 432/80 Primary Examiner.lohn .1. Camby Assistant Examiner-Henry C. Yuen Attorney, Agent, or FirmLearman & McCulloch [57] ABSTRACT A rotary furnace having its discharge end leading to a conical extension that communicates with a plurality of eircumferentially spaced cooling tubes and wherein the conical extension carries an annular member on which a bearing ring is fixed.

4 Claims, 5 Drawing Figures ROTARY FURNACE This invention relates to a rotary furnace with a number of cooling tubes disposed round its outlet end, together with a conically flared end provided at its outlet end and to whose annular terminal wall the cooling tubes are directly connected. A furnace of this general type is disclosed in pending application Ser. No. 232,685, filed Mar. 8, 1972, now US. Pat. No. 3,775,042.

In known rotary furnace constructions, cooling tubes are disposed in satellite manner around the peripheryof the rotary furnace outlet and either have their discharge ends directed towards the inlet end of the rotary furnace (with the cooling tubes displaced around the casing of the furnace outlet end), or extend in the opposite direction away from the furnace outlet end. In the latter case the cooling tubes usually are supported on a support pipe forming in general an extension of the rotary furnace. The hot material leaving the rotary furnace (e.g., cement clinker, calcined clay or the like) is then fed into the cooling tubes through which it passes in counter-flow to the cooling air. For this reason the outlet end of the known rotary furnace is connected to the individual cooling tubes through separately formed tubular connector or transition pieces, extending generally radially, so that on the one hand hot material can reach these cooling tubes, and on the other hand cooling air pre-heated by the material can be fed as secondary air into the rotary furnace. It has now been found that these transition members in the known constructions are subjected to exceptionally high thermal and mechanical stresses and hence have to be constructed to very stringent requirements and at high cost. Also, this type of transition member easily clogs with material, resulting in undesired down-time.

The construction shown in the application above referred to provides for the transition from the rotary furnace outlet end to the cooling tubes in such manner that the defects described for known constructions are avoided. The construction disclosed in such earlier application has a rotary furnace provided at its outlet end with a conically flared portion to whose terminal wall the cooling tubes are connected directly without transition members. In a construction of this type the structurally complicated transition members, with their very high susceptibility to wear, found in known designs can be dispensed with and replaced by a single frustoconical member which is extremely simple to make. By using such a frusto-conical member, the individual cooling tubes can be connected in dust and gas-tight manner to the rotary furnace, without the casing on the furnace outlet end having to be pierced, so that it suffers no weakening in this area as is the case in known constructions, but is in fact further strengthened. This direct connection to the outlet end of the rotary furnace also permits quite direct passage of hot material into the cooling tubes, so that clogging and the disadvantage resulting therefrom can be effectively prevented. At the same time an effective flow route, with relatively small resistance to flow, is provided for the secondary air entering the rotary furnace from the cooling tubes.

In the rotary furnace construction disclosed in the earlier application, the outlet end with the cooling tubes is supported either on a bearing ring alone, discantilevered rear outlet end the furnace outlet end),

the cantilevered rear outlet and with the cooling tubes and the resulting heavy weight necessitate reinforcements in order to support the static streses arising.

With the second bearing ring support (this ring being in the vicinity of the furnace outlet end), the length of the furnace is increased, and further expenditure on design and material is needed.

It is therefore desirable to improve the design disclosed in the prior application to provide further constructional simplification and additional saving of material costs for the outlet end of the rotary furnace.

According to the invention this aim is achieved in that the end of the conically flared extension with the larger diameter has a substantially cylindrical tubular member sufficiently long for the provision of a bearing ring on its periphery. In this way there is needed only one bearing ring in the area of the rotary furnace outlet end, whatever the size and-construction of the furnace. This one bearing ring is also applied to a component, i.e., to the conically shaped extension piece, which in any case represents a reinforcement of the furnace outlet end, so that no additional constructional features are needed to withstand the static stresses in this area. For applying the bearing ring only the said tubular member need therefore be provided, and this hardly affects the all-over length of the rotary furnace.

Further details of the invention will appear from the description below of some embodiments shown in the drawings. In these:

FIG. 1 is a view of the end of a first embodiment of a rotary furnace as provided by the invention;

FIG. 2 is an end view of the furnace shown in FIG. 1; and

FIGS. 3, 4 and 5 are further schematic views of the ends of further embodiments of the invention.

The end of a cylindrical rotary furnace l as shown in FIG. 1 includes a flared portion 2 of frusto-conical shape. On the annular terminal wall 3 of this flared portion 2 there are for example six cooling tubes 4 fixedly attached in satellite manner around the outlet end, and held by at least one holder 5 on a support tube 6 forming the end of the rotary furnace in such manner that thermal expansion is facilitated. To aid clarity only two cooling tubes 4 are shown in FIG. 1; the uniform arrangement of the various cooling tubes 4 can be seen in FIG. 2. More or less than six cooling tubes could naturally be provided. In any case the material inlet ends of these cooling tubes 4 pass through the annular terminal wall directly into the conical extension member 2.

The larger diameter end 2 of the conical extension member 2 has a cylindrical tubular member 15 fixedly connected to it, and which is just long enough to permit attachment of a bearing ring 16. The annular terminal wall 3 and the cylindrical tubular member 15 are both affixed to the end 2' with the larger diameter.

As may also be seen in FIG. 1, the annular terminal wall 3 is connected to the support tube 6 through the cylindrical tubular member and a further, relatively flat frusto-conical jacket 8 pierced by the cooling tubes 4. This leads to better fixation of the cooling tubes 4 on the extension member 2; also the larger diameter end 2' of the extension member is given extra stiffening.

In the embodiment shown in FIG. 3, which includes a further development of the construction shown in FIG. 1, a number of stiffening tubes 11, corresponding to the number of cooling tubes, and which embrace the material inlet ends of the cooling tubes 4, are disposed between the annular terminal wall 3 and the flat frustoconical jacket 8.

A further embodiment of the invention is shown in FIG. 4. In this embodiment the fiat frusto-conical jacket% of the preceding embodiments is omitted, so

that preferably at least two supports 5 backed by a somewhat extended support tube 6 are provided for each cooling tube 4. In this case the annular terminal wall 3' of the conical extension member 2 has the shape of a flat frusto-conical jacket which widens out in the direction towards the material inlet ends of the cooling tubes 4. This construction of the annular terminal 3 prevents the fired material from dropping back into the extension member 2 following entry into the cooling tubes 4.

' While in the preceding embodiments of the invention the cooling tubes extend away from the outlet end of the rotary furnace 1, so that the hot material to be cooled maintains in general the same direction of movement in the cooling tubes 4 that it has in the rotary furnace l, the cooling tubes 4' in the example shown in FIG. 5 run in the opposite direction, i.e., they extend from the outlet end of the rotary furnace towards its inlet end. In this case the individual cooling tubes 4' are arranged in satellite manner round the firing zone of the rotary furnace l, with the outlet ends 14 of the cooling tubes 4' pointing towards the inlet end of the rotary furnace. Since a rotary furnace is generally inclined towards its outlet end, the material to be cooled in the cooling tubes must be conveyed slightly upwards; consequently conveyor means known per se but not shown here are incorporated in the individual cooling tubes 4. Again in this embodiment of the invention the hot material is fed directly into the inlet ends of the cooling tubes 4' through a conical extension member 2a, reversely disposed as in the preceding example. At its end 2a with the larger diameter the extension member 2a again has a cylindrical tubular member 15, on whose periphery is mounted the bearing ring 16. The main advantage of this embodiment lies in the particularly short total length of the rotary furnace provided by the invention. In each of the disclosed embodiments of the rotary furnace in accordance with the invention, only one bearing ring is needed in the area of the outlet end, this being placed at a point which is in any case notable for its special stiffness.

What is claimed is:

l. A rotary furnace comprising a discharge tube having an outlet end, a coaxial frustoconical extension fixedly mounted on the outlet end of said discharge tube and having a large diameter end of a diameter in excess of the diameter of said discharge tube, an integral cylindrical extension mounted upon the large diameter end of said frustoconical extension and projecting coaxially therefrom by a distance substantially less than the axial dimension of said frustoconical extension, a plurality of cooling tubes having inlet ends projecting into said cylindrical extension and fixedly suppported therefrom at symmetrically spaced positions around the axis of said cylindrical extension with the axes of said cooling tubes extending parallel to the cylindrical extension axis, support means cooperatively supporting said cooling tubes in the aforementioned relationship to each other, and an annular bearing ring mounted upon the outer periphery of said cylindrical extension.

2. A rotary furnace as defined in claim 1 further comprising a terminal wall closing the end of said cylindrical extension remote from said frustoconical extension, said cooling tubes projecting through said terminal wall into the interior of said cylindrical extension.

3. A rotary furnace as defined in claim 2 further comprising a plurality of stiffening tubes mounted between said terminal wall and the peripheries of said cooling tubes to provide an axial extension of the support pro vided to said cooling tubes by said terminal wall.

4. A rotary furnace as defined in claim 2 further comprising a support tube fixedly mounted in said terminal wall and extending axially outwardly therefrom in coaxial relationship to the axis of said cylindrical extension, said terminal wall having a frustoconical configuration inclined oppositely to the inclination of said frustoconical extension, and said support means including means supporting said cooling tubes from said support tube.

UNITED STATES PATENT OFFICE- CERTIFICATE OF CORRECTION went o, 3,846,067 Dated November 5, 1974 Inventor) Manfred Durr It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 9 and 10, delete "the furnace outlet end), the cantilevered rear outlet and";

(SEAL) Attest:

c. MARSHALL DANN McCOY M. GIBSON JR.

Commissioner of Patents Attesting Officer FORM PO-IOSO (10-69) I U. 5. GOVERNMENT PRINT NG OFFICE I... O3-S. 

1. A rotary furnace comprising a discharge tube having an outlet end, a coaxial frustoconical extension fixedly mounted on the outlet end of said discharge tube and having a large diameter end of a diameter in excess of the diameter of said discharge tube, an integral cylindrical extension mounted upon the large diameter end of said frustoconical extension and projecting coaxially therefrom by a distance substantially less than the axial dimension of said frustoconical extension, a plurality of cooling tubes having inlet ends projecting into said cylindrical extension and fixedly suppported therefrom at symmetrically spaced positions around the axis of said cylindrical extension with the axes of said cooling tubes extending parallel to the cylindrical extension axis, support means cooperatively supporting said cooling tubes in the aforementioned relationship to each other, and an annular bearing ring mounted upon the outer periphery of said cylindrical extension.
 2. A rotary furnace as defined in claim 1 further comprising a terminal wall closing the end of said cylindrical extension remote from said frustoconical extension, said cooling tubes projecting through said terminal wall into the interior of said cylindrical exteNsion.
 3. A rotary furnace as defined in claim 2 further comprising a plurality of stiffening tubes mounted between said terminal wall and the peripheries of said cooling tubes to provide an axial extension of the support provided to said cooling tubes by said terminal wall.
 4. A rotary furnace as defined in claim 2 further comprising a support tube fixedly mounted in said terminal wall and extending axially outwardly therefrom in coaxial relationship to the axis of said cylindrical extension, said terminal wall having a frustoconical configuration inclined oppositely to the inclination of said frustoconical extension, and said support means including means supporting said cooling tubes from said support tube. 